Communication systems are known by a skilled person. A communication system may provide the user, or more precisely, user equipment or terminal, with connection-oriented communication services and/or connectionless communication services. An example of the first type is a circuit switched connection where a circuit is set-up with call set-up and admission control. An example of the connectionless communication services is a so called packet switched service that is typically used in communication that is based on the Internet Protocol (IP). Both of the circuit switched and the packet switched services can be used for communicating packet data. Packet data services can be defined in general as services that are capable of transporting data units (data packets or similar data entities of fixed or variable length) between two signalling points, such as between two terminals or other nodes of the communication system.
In the connectionless services no circuit is set up, but each data entity itself contains an address. Upon arrival of the data entity in a node the address thereof may be looked-up in a table in the node, and the data entity is transported in the next hop to an address that corresponds to that address entry in the table. Instead of hops, in the circuit switched connections the nodes typically maintain information of how to route/switch each packet belonging to that flow.
The circuit switched networks often have fixed-length packets called cells whereas packet-switched networks carry data units of variable length (e.g., the IP). However, there are also data networks that carry variable length data units in a connection-oriented architecture, such as Multi Protocol Labeled Switched (MPLS) networks.
A network that is capable of transporting data units or data entities between two or more nodes is referred to in the following as a data network. The data network may be a communication network that is based on use of a fixed line or wireless communication media. The wireless connection may be used only for a part of the connection between the two nodes. Examples of data networks, without limiting this disclosure to these, include ATM (Asynchronous Transfer Mode), IP (Internet Protocol) and Local Area Networks (LAN). Examples of communication networks that are capable of providing wireless services, such as IP (Internet Protocol) or ATM/AAL2 (Asynchronous Transfer Mode/ATM Adaptation Layer-type 2) based packet data transmissions, include, without limiting to these, the GSM (Global System for Mobile communications) based GPRS (General Packet Radio Service) network, EDGE (enhanced data rate for GSM evolution) Mobile Data Network and third generation telecommunication systems such as the CDMA (code division multiple access) or TDMA (time division multiple access) based 3rd generation telecommunication systems that are sometimes referred to as Universal Mobile Telecommunication System (UMTS), and IMT 2000 (International Mobile Telecommunication System 2000). All these relate to the transfer of data to and from mobile stations or similar user equipment providing the user thereof with a wireless interface for the data transmission.
A data transmission system and/or the usage thereof can be managed based on several different principles. For example, the usage of the resources of the system may be charged based on counts of the transferred bits, data packets or other units. Schemes such as “charging in the Internet” can be referred to as arrangements which may require the counting of the amount of data that has been transferred. The charging may also be based on a flat fee charging scheme. A monthly flat fee that is charged regardless the actual usage of the resources is an example of the flat fee charging. The charging scheme may also be a combination of several different charging possibilities. In addition to charging, the management includes various other functions such as congestion control, resource management (e.g. resource allocation), configuration of nodes, higher-level management functions such as SLA-verification. Other examples of management operations that are based on traffic flow estimates include multipath routing and load distribution (i.e. data units belonging to a flow between origin and destination may be transferred via different paths, depending on the traffic load on a link), or Differentiated Services (DiffServ) mechanisms such as SIMA (Simple Integrated Media Access) where packets are marked according to utilized bandwidth and usage agreements.
The above aspects, which may be summarised in so called ‘policy-enabled networking’, may require amongst others a smooth estimate of the utilised bandwidth to enable stable and smooth control of the communication in the system. An accurate estimate of the bandwidth that is used by a process, user or group thereof of the communication system is an important feature of the policy-enabled networking. Although the data communication systems may measure the bitrates for the purposes of traffic control (e.g. access control, traffic priority assignment), the inventors have found that the estimation of bandwidth usage and policy enforcement based on these estimates should be handled separately in the communications system, as they are two different processes. The first process relates to the actual traffic while the latter relates to service provisioning.
An example of the policy-enabled networking is Quality of Service (QoS) provisioning using the so called ‘DiffServ’ architecture. ‘DiffServ’ refers to the IP Differentiated Service architecture, where QoS provisioning is obtained by marking of data units. Different marked packets will receive a different priority in queuing and/or scheduling of nodes (so-called Per-hop-behaviour). The marking may dynamically depend on a time-averaged estimate of the data flow. Examples of other functions that may be included in the policy management include features such as configuration management, traffic shaping, congestion control, service level agreement verifications and so on.
A specific example of a DiffServ scheme that is based on the time-averaged estimate of the data flow is so called SIMA (Simple Integrated Media Access) method. However, the inventors have found that the prior art proposals, such as the SIMA bandwidth estimator, may not provide accurate enough estimate of the used bandwidth. In addition, estimation methods such as the SIMA bandwidth estimation may require numerous ad-hoc settings. The SIMA bandwidth estimator is not scalable either and cannot be applied in a distributed manner. A difficulty in estimating the bandwidth is due to the fact that the underlying process, i.e. transportation of data packets or other data entities, is a stochastic process. In other words, in the packet data networks the length of data packets, the amount of data packets and the distance between the subsequent data packets are random variables. Furthermore, for connectionless networks the underlying process is not only not time invariant, i.e. non-stationary, it may be even chaotic in nature. Although the SIMA proposal may work reasonably well in networks that are based on modes such as the asynchronous transmission mode (ATM), the SIMA method may not provide satisfying results in data communication systems that may communicate data with variable packet lengths.
Multipath routing may also be difficult to employ at present as sudden changes in traffic estimates on different links may cause route flaps (sudden changes between two alternate paths). The flaps are at present considered as one of the major causes for network instabilities and may result in inefficient network utilization. Another disadvantages of the methodology presently used in traffic estimates include ad-hoc setting of parameters, discontinous or ill-defined usage estimates that may prevent deployment of predictive network control algorithms such as multipath routing, and non-additivity of the algorithm which may prevent easy and scalable deployment in distributed environments.